Typically, the surfaces of glass fiber substrates are coated with a sizing composition during the forming process to protect the glass fibers from interfilament abrasion. Such sizing compositions can include as components film-formers, lubricants, coupling agents, emulsifiers, antioxidants, ultraviolet light stabilizers, colorants, antistatic agents and water, to name a few.
U.S. Pat. No. 3,853,605 discloses a combined aqueous sizing and coating composition for coating glass fibers shortly after attenuation that includes a resorcinol-formaldehyde resin solution, a styrene-butadiene-vinylpyridine terpolymer latex, an amino functional silane coupling agent, ammonia and an ammonia soluble carboxyl-containing polymer, such as an acrylic interpolymer which can include vinyl aromatic hydrocarbons such as styrene. Similarly, U.S. Pat. No. 4,060,658 discloses an impregnant for glass fibers comprising a resorcinol-formaldehyde resin, a terpolymer latex of butadiene-styrene and vinylpyridine, a butadiene latex, a portion of which can be replaced by a styrene-butadiene copolymer latex, and a wax. U.S. Pat. Nos. 4,164,485 and 4,239,800 disclose an impregnant comprising neoprene latex, styrene-butadiene-vinylpyridine terpolymer latex, resorcinol formaldehyde resin, resorcinol, formaldehyde, wax and natural rubber. The aforementioned coated strands are disclosed for use as reinforcement for elastomeric products such as natural or synthetic rubber. The use of resorcinol-formaldehyde latex coatings, however, gives rise to a number of environmental and health concerns which limits their use.
U.S. Pat. No. 4,663,231 discloses an impregnant for glass fibers for woven fabric comprising an elastomeric, ethylene-containing interpolymer, a crosslinkable material, and a diene-containing elastomer.
U.S. Pat. No. 5,182,784 discloses an aqueous coating composition for glass fibers consisting essentially of a thermoplastic polyurethane latex, an acrylic latex, and either a second acrylic latex or paraffin wax. This coating reduces water wicking by glass fibers in applications such as optical fiber cable reinforcement.
In optical fiber cable reinforcement applications, water entering the cable assembly can corrode and/or crush the optical fibers by expansion due to freezing temperatures. It is desirable to provide an optical fiber cable assembly in which the reinforcing glass fibers are coated with a simple, economical secondary coating which can withstand the rigorous environment to which such reinforcement is subjected, as well as provide water wicking resistance characteristics to the reinforcement.